Constraining the FRB Central Engine from Flux Variations of Persistent Radio Sources: FRB 20240114A as the First Attempt
Abstract
Some repeating fast radio bursts (FRBs) are associated with persistent radio sources (PRSs), likely driven by the long-term activity of a central engine. We investigate FRB 20240114A-currently the most active repeating FRB-to explore the link between its burst activity and the flux variability of its associated PRS. We model electrons responsible for FRB emission being continuously injected from a central magnetar into its magnetar wind nebula (MWN), where synchrotron radiation produces the PRS. Comparing our model with the latest PRS spectra and flux variations, we constrain the physical properties of the FRB source. We find that the total energy injected into the MWN during FAST observations from January to August 2024 is ∼ 1048 erg, consistent with the magnetic energy budget of a magnetar with an internal magnetic field of ∼ 1016 G. The bulk Lorentz factor of the FRB-emitting plasma is mildly constrained to ≲ 103, and FRB 20240114A is inferred to be powered by a young magnetar aged ∼ 10-20 yr. These results show that the PRS flux variability effectively probes FRB emission properties. We predict that while PRS luminosity increases rapidly with enhanced FRB activity, it will slowly fade over decades via adiabatic cooling after FRB activity ceases. Energetics suggest that the hyper-active phase observed in FRB 20240114A (burst rate ∼ 700 hr−1) is a rare state with a duty cycle of ≲ 10−2, which is broadly consistent with its detection rate in current FRB-PRS samples.
Related
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BibTeX
@misc{matsumiya2026constraining,
title = {{Constraining the FRB Central Engine from Flux Variations of Persistent Radio Sources: FRB 20240114A as the First Attempt}},
author = {Hirotaka Matsumiya and Kazumi Kashiyama and Tomonori Totani},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27489},
eprint = {2610.27489},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27489},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Constraining the FRB Central Engine from Flux Variations of Persistent Radio Sources: FRB 20240114A as the First Attempt
AU - Hirotaka Matsumiya
AU - Kazumi Kashiyama
AU - Tomonori Totani
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.27489
UR - https://arxiv.org/abs/2610.27489
AB - Some repeating fast radio bursts (FRBs) are associated with persistent radio sources (PRSs), likely driven by the long-term activity of a central engine. We investigate FRB 20240114A-currently the most active repeating FRB-to explore the link between its burst activity and the flux variability of its associated PRS. We model electrons responsible for FRB emission being continuously injected from a central magnetar into its magnetar wind nebula (MWN), where synchrotron radiation produces the PRS. Comparing our model with the latest PRS spectra and flux variations, we constrain the physical properties of the FRB source. We find that the total energy injected into the MWN during FAST observations from January to August 2024 is ∼ 10^48 erg, consistent with the magnetic energy budget of a magnetar with an internal magnetic field of ∼ 10^16 G. The bulk Lorentz factor of the FRB-emitting plasma is mildly constrained to ≲ 10^3, and FRB 20240114A is inferred to be powered by a young magnetar aged ∼ 10-20 yr. These results show that the PRS flux variability effectively probes FRB emission properties. We predict that while PRS luminosity increases rapidly with enhanced FRB activity, it will slowly fade over decades via adiabatic cooling after FRB activity ceases. Energetics suggest that the hyper-active phase observed in FRB 20240114A (burst rate ∼ 700 hr^−1) is a rare state with a duty cycle of ≲ 10^−2, which is broadly consistent with its detection rate in current FRB-PRS samples.
ER -